A fistula is an abnormal connection between organs. The rate of occurrence of leaks and fistulas following bariatric surgery ranges from 0.5% to 5%. These occur at staple lines in the gastric pouch or gastrojejunostomy in gastric bypass patients. Despite their relatively low incidence, leaks through fistulas can be life threatening and costly due to increased hospital stays and the need for antibiotics and parenteral nutrition. Regardless of its origin, pouch or gastrojejunostomy, fistulas can reach the skin (gastro- or enterocutaneous), the peritoneal cavity (abscess or peritonitis), adjacent stomach or bowel (gastro-gastric or gastro-enteric), and even the thorax and mediastinum.
The conventional treatment for relatively benign leaks is Nothing Per Oral (NPO) with parenteral nutritional support until the leak or fistula heals. If there is concurrent infection and sepsis, re-operation to suture, drain and gain enteral nutrition access may also be needed.
Experimental endoscopic approaches are being tried to close these leaks. These methods to close the fistula include fibrin glue, endoclips and packing the fistula with various biomaterials. These approaches result in successful healing in up to 70% of the cases, but they require at least three procedures per patient. Less severe gastro-enterostomy leaks and fistulas generally heal without intervention or with one endoscopic treatment. Gastric pouch fistulas are more difficult to close as surgical attempts generally fail.
FIG. 1 is a sectional view of a portion of the digestive tract in a body. Food to be digested enters the stomach 102 through the cardiac orifice 110 from the esophagus 120. The esophagus 120 is a tube that connects the pharynx (not shown) with the stomach 102. In an adult, the esophagus 120 may be about 10 inches long (250 mm). When a person swallows, the muscular walls of the esophagus contract to push food down into the stomach 120. Glands in the lining of the esophagus produce mucus, which keeps the passageway moist and facilitates swallowing. The Gastroesophageal (GE) Junction 122 has two sides, the esophageal side and the gastric side. The Lower Esophageal Sphincter (LES)) encircles the esophagus at the GE Junction 122 and is normally contracted to close the esophagus 120. When the GE Junction 122 closes, the contents of the stomach 102 cannot flow back into the esophagus 120.
Chyme, a semi-fluid, homogeneous creamy or gruel-like material produced by gastric digestion in the stomach exits the stomach through the pyloric orifice (pylorus) 108 and enters the small intestine 112. The pylorus 108 is a distal aperture of the stomach 102 surrounded by a strong band of circular muscle. The small intestine, about nine feet in length, is a convoluted tube, extending from the pylorus to the ileo-caecal valve where it terminates in the large intestine. The small intestine 128 has three sections, the duodenum 104, the jejunum 106 and the ileum (not shown). The first eight- to ten-inch section of the small intestine 128, the duodenum, is the shortest, widest and most fixed part of the small intestine.
The duodenum 104 has four sections: superior, descending, transverse and ascending which typically form a U-shape. The superior section is about two inches long and ends at the neck of the gall bladder. The descending section is about three to four inches long and includes a nipple shaped structure (papilla of vater) 114 through which pancreatic juice from the pancreas and bile produced by the liver and stored by the gall bladder enter the duodenum from the pancreatic duct. The pancreatic juice contains enzymes essential to protein digestion, and bile dissolves the products of fat digestion. The ascending section is about two inches long (50.8 mm) and forms the duodenal-jejunal flexure 116 where it joins the jejunum 106, the next section of the small intestine. The duodenal-jejunal flexure 116 is fixed to the ligament of Treitz 118 (musculus supensionus duodeni). The juices secreted in the duodenum break the partially digested food down into particles small enough to be absorbed by the body. The digestive system is described in Gray's Anatomy (“Anatomy of the Human Body”, by Henry Gray) and “Human Physiology”, Vander, 3rd ed., McGraw Hill, 1980, the contents of which are incorporated herein by reference in their entireties.
Gastric bypass surgery makes the stomach smaller and allows food to bypass part of the small intestine. A person will feel full more quickly than when the stomach was its original size, which reduces the amount of food one can eat and thus the calories consumed. Bypassing part of the intestine also results in fewer calories being absorbed. This leads to weight loss. The most common gastric bypass surgery is a Roux-en-Y gastric bypass. FIG. 2A is a sectional view of one surgical approach to a Roux-en-Y gastric bypass procedure. In this procedure, the surgeon first divides the stomach and creates a small stomach pouch 202 using staples 206, and then constructs a “bypass” for food. The small pouch 202 is about 40 to 60 cc. The bypass allows food to skip parts of the small intestine 128. By skipping a large part of the small intestine 128, the body cannot absorb as many calories or nutrients.
To make the bypass, the surgeon then makes a cut about one foot below the stomach 102 (Points A and B), which may be in the jejunum 106. Then a new 0.5 inch (15 mm) opening (stoma) is created in the small stomach pouch 202 (Point C). Referring to FIG. 2B, the surgeon then attaches the open end of the small intestine (Point B) to the new opening at Point C, creating a Roux limb 208. The Roux limb 208 carries food and fluids from the stomach pouch 202 into the lower portion of the small intestine 128.
The remaining end at Point A is stapled to close the opening. A new opening is created at Point D. The surgeon attaches Point A′ to the new opening at Point D, creating a “Y-shaped” or “Y-limb” intestinal junction 210. The Y-limb carries digestive juices from the bypassed stomach, pancreas, liver, and duodenum to the remaining intestines. The opening is made at Point D to allow digestive juices to flow into the lower portion of the small intestine 128.
Although the Roux-en-Y Procedure is an effective weight loss procedure, there are risks associated with such a procedure. For example, fistulas 205 and leaks can occur at the staple linings 206 and more typically at the stoma (Point B to C). Attempts have been made to treat these fistulas and leaks surgically and by covering them with stents that were typically designed to open strictures. For example, the Ultraflex™ Esophageal NG Stent System and Polyflex™ stents by Boston Scientific Corporation and the stents by Cook® Medical Incorporated, as well as the Choo stent (for example as in the Journal article by Steimann, R. U.; Zundler, J.; Kreichgauer, H. P.; Bode, J. C. (2000). A new stent device (Choo stent) for palliation of malignant gastric outlet obstruction. Endoscopy, 32 (5)) have been used to cover fistulas and/or leaks.